Functional capacity of NK cell subsets in chronic HIV-1 infection. Primary flow data and dot plots represent pattern of IFN-γ secretion (A) and CD107a expression (B) following stimulation with MHC-devoid K562 cells. Similarly, primary flow cytometry results and dot plots represent the level of IFN-γ secretion (C) and CD107a up-regulation (D) following stimulation with phorbol 12-myristate-13-acetate (PMA)/ionomycin for the 3 subsets of NK cells for the untreated viremic (▪), treated viremic (⋄), treated aviremic (•), nonprogressors (▿), and subjects without HIV-1 infection (▴).